Study of thermal transport in nanoparticle suspensions using forced Rayleigh scattering

Thermal diffusivity measurements on two nanofluids and their base fluids were made using an optical technique called forced Rayleigh scattering. The nanofluids studied were a citrate-stabilized Au nanoparticle suspension in water and an Al2O3 nanoparticle suspension in a petroleum oil. Thermal diffusivity measurements on the nanofluids and base fluids were made at temperatures in the range of 25–75°C. From these data, it was possible to estimate the thermal conductivity enhancement in the nanofluids as a function of temperature. In contrast to previous reports on similar systems, our experiments are consistent with thermal conductivity enhancement predictions from effective medium theory. In particular, we find that the level of thermal conductivity enhancement is independent of temperature.